A buoyancy control device (BCD), also known as a buoyancy compensator (BC), is a piece of diving equipment worn by a diver, that assists the diver to regulate and control his or her overall buoyancy relative to the water. The purpose of the buoyancy control device is to assist the diver in obtaining neutral buoyancy wherein the weight of the diving equipment is cancelled out, thus allowing the diver to ascend and descend in a controlled manner. The buoyancy control device also provides positive buoyancy when a diver is at the water surface, thus allowing the diver to float irrespective of the heavy equipment and diving suit being carried.
A buoyancy control device typically includes a harness component that is worn by the diver, and to which diving cylinder(s) are also secured. The buoyancy control device also includes an air cell or bladder, which is attached to the harness and is selectively inflatable and deflatable to provide positive buoyancy at the surface, or neutral buoyancy underwater.
Buoyancy control device designs known in the art typically utilise a harness constructed of various layers of fabric, foam and/or plastic backing stitched together so as to form composite shoulder straps, waist closures and a back section. The back section often also includes a rigid plastic or metal back plate for additional structural support of the cylinder.
The above design essentially comprises a plurality of fabric layers being stitched or otherwise joined together so as to form a composite buoyancy control device. By the very nature thereof, this process is time-consuming, laborious and thus costly. Further, as most fabrics used are water absorbent, the buoyancy control device remains wet long after having been used in a dive. Also, fabrics are prone to degradation due to continued exposure to chemicals and sunlight.
The air cells or bladders are usually manufactured from sheets of polyurethane, or nylon with a polyurethane backing. Sheets are located adjacent one another so that the sheets substantially overlie one another, and a seam is subsequently formed by gluing or welding the edges of the sheets together. Thereafter a bead is usually stitched around the border of the air cell. However, most failures of buoyancy control devices are related to stitching coming loose or failure of an air cell or bladder seam.
Prior art harness for buoyancy control devices known to the Applicant includes FR 1235501 which describes a dorsal plate which serves as a carrier for a compressed air cylinder for underwater diving. It has a loop at the top to engage the collar of the cylinder and two attachment points for attaching straps for carrying on the back of a diver. This is an early arrangement for diving which was in existence prior to the arrival of buoyancy control devices in their current form. This arrangement includes attachments for shoulder straps made of webbing but would be used without an inflatable air cell or with an inflatable collar (similar to a life jacket) to increase the buoyancy of the diver. It therefore differs from and could not be used with a buoyancy control device comprising a backpack or harness including an inflatable cell. In addition the method for holding the dorsal plate onto the diver is not described—this being fundamental to applicant's invention.
A further patent, GB 1546755 describes a detachable mounting plate for a cylinder. In this case it is clear that this is attachable to a harness or backpack for use by a diver. The patent drawings (FIG. 1) illustrate a type of rubber harness shown as a one-piece construction (similar to a bib) and secured by waist buckles. This harness is neither described nor claimed in the patent. Apart from the fact that this comprises a unitary construction as opposed to multi-component construction of the current invention, this would be an ungainly, impractical and ill-fitting harness which was possibly used for a short time if at all, until progress realised improved versions. Given that the invention of GB 1546755 was in fact a novel dorsal plate for a diving harness, FIG. 1 may have been used purely for illustrative purposes. In the event that this bib-type harness was used, it would in all likelihood have been cut from a flat sheet of rubber or other material. Any attachments would need to be glued, riveted or stitched on whereas the applicant's invention is specifically a moulded construction that allows all attachments, logos and the like to be integrated into the design. Furthermore, the design of the bib would, by nature of its unitary construction, have no shoulder-strap/torso-length adjustment, very limited waist adjustment and, very importantly, no means of removal by the diver easily in the case of an emergency. In addition, with the unitary design, different sizes would require totally different components. The benefit of the applicant's modular design is that the back plate is common but the sizing is easily changed by fitting different sized shoulder straps and/or waist straps.